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Ferrite core inverter full bridge problem.

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ai.nayem

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Actually i use a full bridge mosfet circuit after a 320v ferrite core inverter.
This circuit i found from google search.
But the low side mosfet getting extremely hot in few second.
Please help anyone. Please
 

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ai.nayem said:
Actually i use a full bridge mosfet circuit after a 320v ferrite core inverter.
This circuit i found from google search.
But the low side mosfet getting extremely hot in few second.
Please help anyone. Please
Click to expand...
 

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I guess your SG3525 chip creates SPWM?
Possibilities:

* When running square waves through inductors... Abrupt shut-off generates high-voltage spikes at each cycle. This puts enormous stress on switching transistors.

* Or when biasing transistors with sine waves ... Then the transistor spends a large percentage of cycle time in resistive mode (as opposed to entirely On-Off mode). This produces wasteful heat.
 

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cupoftea said:
you used heatsink? You have fans?
Click to expand...
Yes.....
I use heatsink only.
A 100watt bulb load this low side mosfet getting extremely hot just few second, can burn my skin.
I identify my mosfet are not orginal, its fake & cheap.

Fake mosfet, its the reason for hot?
Sorry for my english.
 
Last edited:

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Each mosfet in your H-bridge needs a correct bias voltage which: a) turns it entirely Off, and: b) another bias voltage which turns it entirely On. (This assumes bias waveform is not sine waves.)

High side switching requires different volt levels from low side switching.

If bias voltage is outside the correct range, you get improper turning On & Off. You may perforate a plain mosfet's gate. I'm unaware of details about SG3525 function.

It takes some doing to confirm current flows at the proper times in a cycle. Did you test each mosfet individually with various loads?
 
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